The present invention relates to stereomicroscopes of a type comprising an objective having an optical axis; a zoom system downstream of the objective having a plurality of axes, at least one of which forms an angle with the optical axis of the objective; another axis extending substantially parallel to the at least one axis of the zoom system; and a plurality of deflector elements for guiding at least one observation beam emerging from the objective into the zoom system and for guiding at least one observation beam emerging from the zoom system on to the other axis that is substantially parallel to the at least one axis of the zoom system.
Operating microscopes used in ophthalmology and neurosurgery make it possible for both a main operator and an assistant to view the same operating area.
An ophthalmological operating microscope of this kind is known for example from DE 43 31 635 C2. The operating microscope described therein has binocular tubes for the main observer and a second observer as well as a beam splitter 4 which divides the object light between the main observer and second observer. A disadvantage of this microscope is that it is relatively tall in construction as the complete magnification optical means for the main observer are arranged substantially vertically.
A stereomicroscope for use in neurosurgery for simultaneous observation by a first and second observer is known from DE 33 33 471 C2. The optical paths are divided for the first and second observer by a dividing plate, as a result of which some loss of light intensity has to be tolerated. In addition, the free working space between the objective and the object is greatly reduced.
Finally, a similar microscope is known from U.S. Pat. No. 5,898,518.
Operating microscopes of this kind have to satisfy a number of basic requirements in practice.
One requirement is that the overall height of the microscope must be kept to a minimum for ergonomic reasons. In addition, the assistant's viewer must be able to be pivoted from the right to the left hand side of the microscope (or vice versa) quickly and with no adaptation required, and neither the image quality nor the overall height should be negatively affected by any accessories (optical or optical/mechanical equipment) which are required only for certain operating techniques. Also, both the main observer and the assistant should have the opportunity to observe the so-called red reflex to the same degree.
In conventional microscopes these requirements are only partly met.
The operating microscope M840/M841 of the present Applicant, for example, ensures that the assistant and main operator actually have the same field of vision.
This is achieved by mounting the assistant's viewing device above the magnification system and using, as the magnification system, a zoom system which is made up of four identical monoscopic magnification systems. Two of the four parallel systems make up the stereoscopic magnification system for the main observer. Further systems or channels located perpendicularly on the connecting axis of these systems provide the stereoscopic magnification system for the assistant.
U.S. 2001/001 05 92 A1 discloses a microscope which can be used in neurosurgery, which comprises an objective system, a zoom system and an eyepiece system. The objective system is mounted substantially vertically, while the zoom system consisting of two individual systems or optical channels is mounted horizontally. The essential novelty of the microscope described therein is that the axis of the zoom system is located perpendicularly to the axis of the main objective. The zoom system consists of two identical magnification channels the axes of which extend parallel to each other, thereby ensuring stereoscopic viewing of an object. One disadvantage of the microscope described therein is that as a result of the use of a semi-transparent beam splitter for spatially separating an assistant's optical path from the main operator's optical path, relatively great loss of light is unavoidable. As the beam splitter of the assistant's microscope also has the illuminating optical path passing through it, reflections are formed there, which are extremely difficult to eliminate. The observing optical path passes convergently through this beam splitter and thus leads to image errors which are difficult to eliminate. In addition, this arrangement of the beam splitter allows for an astigmatism which depends on the relative orientation of the assistant's microscope to the main microscope.